It is common to detachably attach various functional units to the main body of image forming apparatuses such as electronic copying machines, printers, facsimile machines, and multifunction products. A process cartridges, which is disclosed in Patent Document 1, having an image carrier, a developing unit, a cleaning unit, a fixing unit, and an intermediate transfer unit is an example of the functional unit. Such functional units are generally set deep inside the main body of the image forming apparatus. If the functional unit is not set in its usual position, and if the image forming operation starts, an abnormal image can be formed, or, parts in the image forming apparatus can get damaged.
There is a known configuration in which, at the time of attaching a face plate to a front plate of the image forming apparatus main body, the functional unit is pushed in and positioned at the innermost position within the image forming apparatus main body by the face plate, and the functional unit is locked at that position. According to this configuration, since the functional unit can be locked at a predetermined attaching position within the image forming apparatus main body, occurrence of the drawback described above can be prevented. However, when the functional unit is pushed in by the face plate, large external force is applied to the face plate from the functional unit, and the face plate can be largely elastically deformed. In such case, since the face plate serves to position respective elements within the image forming apparatus main body, positions of the elements to be positioned by the face plate may deviate from predetermined positions.
Patent Document 1: Japanese Patent Application Laid-Open No. 2004-240354